The use of telematics systems that integrate wireless communications, vehicle monitoring systems, and location devices is known in the art of vehicle and system monitoring. Telematics systems are often used for the collection and monitoring of vehicle conditions, where the collection of information such as engine RPM, oil pressure, braking, hours of operation and engine temperature is made on vehicles such as cars or trucks. In addition to monitoring engine conditions, telematics systems may be used in vehicles for a variety of other functions, such as sensing a crash and alerting emergency personnel, or detecting the theft of a vehicle. Telematics systems are often employed by businesses that use fleets of vehicles so that the need for maintenance and repairs and the security of personnel and cargo can be monitored.
Telematics systems are also used to monitor the security or status of many types of cargo, both when such cargo is in-transit and when such cargo is in storage. For cargo that is not hazardous in nature, a simple switch that detects the opening or closing of doors or covers may be linked to a telematics system that remotely notifies a user of the status, or change in status, of a door. The switches and systems used in these systems are usually magnetic contact switches like the type used to monitor the doors and windows in a home alarm system.
The use of telematics systems, and electronics generally, in the protective housing, or dome, of tank cars used to ship (either by rail or by roadways) or store hazardous chemicals presents special problems not addressed by the prior art. Properties which make a chemical hazardous, such as reactivity, combustibility, and flammability, necessitate the use of special equipment in the tank cars for the safe transport and storage of the materials. For example, it is necessary to ensure that devices used in the transport and storage of hazardous materials do not produce sparks as these could react with the hazardous materials and result in a fire or an explosion. In addition, the devices used must not be susceptible to vapors from corrosive chemicals that could render them inoperable.
The use of sensors in the protective housing of tank cars also presents special problems because of the lack of space within the protective housing of a tank car. Railroad tank cars and over the road tank trucks used for the transport and storage of hazardous chemicals have significant structural elements to ensure the vessels remain stable and intact under a wide variety of conditions. Railroad tank cars have contained circular areas on the top of the railcar, known as protective housings, manway covers and also domes, which house and protect the valves that provide access to the contents of the railcar. Within the protective housing there is also an access port that allows personnel to physically enter the tank. This access port is normally closed and secured to the tank with large nuts and bolts. The combination of the valves and access port nuts and bolts within the protective housing occupy most of the space within the housing, making it difficult to place additional items, such as sensors, within the housing of a railcar.
Another consideration that has made it difficult to use sensors in a protective housing with a telematics system is the rugged physical environment of the housing. Due to the potentially hazardous nature of the cargo in tank cars, personnel who repair, maintain, load, and unload the tank cars are often required to wear a variety of specialized protective gear when using the valves or otherwise working within the protective housing of the tank car. That gear is typically bulky and may obscure vision, requiring that any equipment within the protective housing be able to withstand accidental contact by the personnel, their gear, and by the tools being used by the personnel (which are large because of the size of the nuts and bolts used within the hatch). The magnetic contact door sensors of the prior art are not able to withstand the environment within a protective housing of a tank car.